"Materials Studio" Simulation Study of the Adsorption and Polymerization Mechanism of Sodium Silicate on Active Silica S
- PDF / 1,882,948 Bytes
- 8 Pages / 595.276 x 790.866 pts Page_size
- 92 Downloads / 158 Views
ght Ó 2020 American Foundry Society https://doi.org/10.1007/s40962-020-00548-6
Abstract Due to its excellent thermal stability, low cost and environmental performance, sodium silicate is expected as one of the binders for core making to realize environmentally friendly casting production. Although a large number of experiments have made insights into the chemical mechanism of active silica–sodium silicate materials, the behavior and characterization of sodium silicate and active silica materials are still unclear. In this study, Materials Studio was used to study the adsorption and molecular dynamics changes of sodium silicate molecules on the surface of active silica (1 - 1 1) at different temperatures. It is a modeling and simulation environment designed to allow to predict and understand the relationships of a material’s atomic and molecular structure with its properties and behavior. With this, one can construct, manipulate and view models of molecules, crystalline materials, surfaces, polymers and mesoscale structures. Materials Studio includes quantum, atomistic, mesoscale and statistical methods that enable one to evaluate materials at
various particle sizes and time scales. It also includes tools for evaluating crystal structure and crystal growth. The results show that sodium silicate can adsorb on the –OH of active silica, and the density of states shows that the energy and DOS of O in Si–OH in active silica are higher than that of ordinary silica O atoms, which provides reactivity for Si–OH on the surface of active silica, which in turn plays a role for promoting sodium silicate polymerization during the sand hardening process. Temperature is an important factor that helps the sodium silicate molecules react and polymerize with the Si–OH in the active silica. This study provides support for the chemical reaction mechanism of sodium silicate at different temperatures on the surface of active silica.
Introduction
for sodium silicate sand,1–7 the use of active/inactive silica is used in the strengthening mechanism and chemical effects of sodium silicate and silica surface film are not yet clear. Inactive silica is a periodic structure of –Si–O–Si–, while the –Si–O–Si– bond of active silica is prepared on the surface to form –Si–OH. The –Si–OH makes the silica have activity. Experiments have found that active silica participates in the polymerization reaction of the binder during the hardening process, which can enhance the strength of use and improve the resistance to moisture absorption.8 However, the mechanism of action between active silica and low modulus sodium silicate molecules at different temperatures cannot be characterized, which makes the mechanism of action of active silica in casting
The sodium silicate binder has been re-emphasized due to its high strength, low cost, thermal stability and environmental protection in casting production. The core technology is also constantly optimized. The more prominent technology is that active silica is added to sodium silicate sand, which is found to be
Data Loading...
